This is how we do our various installations, from french drains to concrete. Our process does not change.
Drainage FAQ
This section has different terms and a bit of info about each.
French Drain
This is a touchy subject as I have seen these installed every which way you imagine. There is only 1 way to install a french drain with the differences being required depth for effective drainage. We excavate the area for the drain (do not use a trencher as they are not wide enough for the gravel and pipe) to a depth of at least 10" possibly more depending on the circumstances, checking for fall as we go. Next we line the ditch on the bottom, up the sides with enough to cover the top with geotextiles filter fabric. Next we install several inches of clean gravel, followed by a corrugated or pvc drainage pipe with holes faced down, followed again by another 10-14" of clean gravel. Finally we wrap the geotextiles filter fabric over the top creating a proper encapsulated french drain. The french drain will exit to daylight with either a pop-up emitter or into a dry creek, ditch line etc. The final step will be either topsoil, seed and straw over the top or gravel to the top which we call an open french drain.
Swale
A swale is basically a gentle roll in the terrain, it is created by making a shallow channel that has softer sides that can be used to channel water run off out of a specific area. They can be landscaped into an area and can be planted with grass or other ground cover. They are often used when a traditional ditch isnt desired but typically can not handle as much flow as a ditch can.
Berm
A berm is simply mounded up soil that acts as a border for water run off. They are built in a way that they can also be used for privacy when smaller shrubs or flowers are planted on the sides and top, creating a functioning solution to directing water and serving as a landscape feature for various plants.
Channel Drain or Trench Drain
Channel drains are used to capture surface run off water in driveways, along a garage or carport or in larger slabs, parking areas that drainage might be difficult. They are a channel, or U shaped with either removable plastic or metal grates on top to aid in cleaning. The channel drain is placed in concrete, asphalt or gravel and can be connected to each other to form longer runs as needed. They come in sizes from 1" up to several feet in width and connect to pipe under the surface that will eventually exit to daylight or a suitable area that the water can drain.
Catch basin
Catch basins are ideal if water is focused to one area, or multiple areas that are designed for the water to flow to. They come in either round or square from 3" up to 24"x24" and larger if needed. They sit slightly below the surface and allow water run off to go into the catch basin which is connected to a pipe underground that routes the water to an acceptable place for release, away from your structure. They can be installed in series, connected via pipe to cover larger areas.
Concrete FAQ
When installing concrete, its essential to have a good base and proper concrete strength and thickness. Do it properly the first time.
Base for concrete
Its important that the base for concrete is properly prepared. Often concrete is poured direclty on the ground and that is never sufficient. First we remove the top layer of grass, vegatation, top spoil or whatever it is and determine the soil type. Here, in North Carolina we have several soil types and they need to be addressed differently. If you have a sandy soil that supports weight well you might be able to excavate the depth of the concrete pour and proceed with compaction and pouring the concrete. If you have a clay based soil, that needs to be undercut an additional 4"' with a clean gravel base installed and compacted before you proceed to pour the concrete.
Concrete strength
Concrete comes in various strengths which are rated in psi. We use at a minimum 3500 psi fiber reinforced concrete poured between a 4"-5" slump. Concrete slump is basically how workable the concrete is, the more water added the higher the slump, the more fluid the concrete flows when wet. Concrete at or over a 6" slump will have difficulties supporting the aggragate in the concrete itself as once its too wet the aggragates will simply fall to the bottom of the concrete and not be suspended through out the concrete which is required for proper strength to be achieved. Simply put, though more water makes it easier to work with too much also weakens the final product.
Concrete thickness
Regardless of the psi rating, concrete needs to be poured at a minimum of 4" for sidewalks, driveways etc that will generally only see foot traffic or residential vehicles. If its something that heavier vehicles will be driven on it's recommended to go with 6-8" and 4000 psi fiber reinforced concrete at the minimum.
Concrete curing times
Concrete will generally cure to a point you can walk on it in 24 hours without harming the surface, sooner but minor surface scuffing could occur. It will generally be vehicle ready in 7 days as its reached about 75% of its rated strength and by 28 days the curing process will have slown down to the point that its considered fully cured although it will actually continue curing for years to come.
Concrete expansion joints
The promise with concrete that it will not crack is a myth. The real promise is that concrete will crack but hopefully it cracks where planned. You want to have expansion joints, either tooled in while pouring or cut in with a saw within 6-18 hours of finishing. Joints should be equally spaced, full length or to an adjacent joint and should be placed every 5' for a walk and 10-14' for slabs or driveways, be a depth of a 1/4" per inch of concrete. Example would be a 4" thick slab would have a 1" expansion joint.